The present invention relates to an anticancer agent, i.e. an anti-malignant tumor agent, for suppressing cancer growth, and more particularly, to an anticancer agent, i.e. an anti-malignant tumor agent, containing diphenylmethylpiperazine derivatives and for suppressing the growth of cancer cells of mammals including human. The present invention also relates to a fibrosis inhibitor for treating proliferative lesions of pulmonary fibrosis (fibroid lung) disease due to fibroblastic proliferation and pulmonary fibrosis disease due to fibroblastic proliferation as side effects of anticancer agents, and more particularly, to a fibrosis inhibitor containing diphenylmethylpiperazine derivatives and for treating proliferative lesions of mammals including human.
Anticancer agents or anti-malignant tumor agents include (1) a nitrogen mustard group, such as melphalan, mechlorethamine and cyclophosphamide, (2) a nitrosourea group, such as BCNU, CCNU, methyl-CCNU and ACNU, (3) an azirine group and an epoxide group, such as thiotepa, mitomycin AZQ, carboquone, dianhydrogalactitol and dibromodulcitol, (4) alkylating agents, such as procarbazine, dacarbazine, and hexamethylenmelamin, (5) antimetabolites including methotrexate (MTX), 6-mercaptopurine (6-MP), 6-thioguanine (6-TG), and 5-fluoropyrimidine such as 5-fluorouracil (5-FU), tegafur, UFT, 5xe2x80x2-DFUR and HCFU, and analogue compounds thereof, (6) anticancer agents derived from plants including vinca alkaloid compounds such as vincristine, vinblastine and vindesine, etoposide compounds such as etoposide and teniposide, a taxane group such as paclitaxel and docetaxel, and camptothecin compounds such as irinotecan, (7) anticancer antibiotics such as adriamycin, serbidine, actinomycine D, cosmegen, preno-xanthan, mutamycin, metamycin, and novantron, (8) hormone agents such as adeno-corticoid, estrogen, progesterone, antiestrogen, aromatase inhibitor, androgen, antiandrogen and LH-RH analogues, (9) enzymes such as L-asparaginase, (10) platinum complex compounds such as cisplatin, carboplatin and nedaplatin (254-S), (11) nonspecific immunostimulants, (12) interferon, and (13) a TNF group.
Along with the establishment of medical treatments by the use of these anticancer agents, a patient of acute lymphatic leukemia, Hodgkin""s disease or the like has had considerably high possibility of returning to social life. However, a patient involved with solid cancers, such as gastric cancer, lung cancer and colon cancer, largely relies upon surgical and radiation treatments. Cisplatin has been used in the treatments of these solid cancers because of its broad antitumor spectrum. However, cisplatin has a problem of confirmed toxicities, such as nephrotoxicity, gastrointestinal toxicity, auditory toxicity and peripheral nerve toxicity, and its low cure rate.
Further, it is known that some anticancer agents superinduce pulmonary fibrosis as side effects, which has serious impact on life prognosis.
It is an object of the present invention to solve these problems of the anticancer agents.
It is an object of the present invention to provide compounds, salts thereof and derivatives thereof, which have a property of exhibiting a significant anticancer activity (or anti-malignant tumor activity) against various cancers or suppressing proliferation of pulmonary fibroblast, or combinedly have both properties of exhibiting a significant anticancer activity (or anti-malignant tumor activity) against various cancers and suppressing proliferation of pulmonary fibroblast, as well as a desirable low toxicity.
The inventors have discovered that compounds represented by the following general formula [1]; 
wherein R represents; 
salts thereof, derivatives thereof or prodrugs thereof have a less toxicity than that of cisplatin, and have a greater carcinostatic effect on various cancers and fibroblastic proliferation suppressing effect than those of cisplatin, and have then completed the present invention.
That is, the present invention is an anticancer agent containing a compound represented by the following general formula [1]; 
wherein R represents; 
a salt thereof, a derivative thereof or a prodrug thereof.